Machine to machine (M2M) establishes wireless connections and enables data transmission between devices of networks, remote equipments and individual users in a real time manner. M2M can include a combination of techniques, including data collection, GPS, remote monitoring, telecommunications, and information technologies. M2M is, in some respects, an ecosystem including computers, networks, devices, sensors, and human beings. M2M enables service process automation, integrates information technology systems with real time states of non-IT devices of a company, and creates value-added services.
In practice, current M2M is used in public network services, i.e., for communications between human and machine or human and human. Since there are mass amounts of M2M service, the number of M2M terminals is also tremendous, e.g., a cell may serve tens of thousands (or even hundreds of thousands) of M2M terminals. When a huge number of M2M terminals access the network at the same time, network access congestion may occur, and a base station cannot provide network access for too many M2M terminals simultaneously.